Aura being global and only affecting ranged heroes (???) is stupid. I would change it but I have no idea
Make the ult completely different and give her a decent agi gain. Maybe give bonus damage for hitting an enemy in the face (or in the back, depends on how you rework aura and frost arrows)
Frost arrows are alright I suppose, but the fact that pros skip it completely tells a lot. Just like old shrapnel, maybe nerf the slow a bit but add an AS slow
Drow drafts are always like "pick 3 or 4 ranged heroes along with her, get medallion on some hero and level 6 on drow, get rosh then 5man win"
The problem with frost arrows is that fundamentally, Skadi is basically better. Skadi pierces BKB, stacks with lifesteal, has no mana cost, and slows attacks as well as movement. Skadi also adds a ton of HP, a decent amount of agility, etc.
The only advantage frost arrows have as the game progresses is that they have a greater movement slow at 3 and 4 points. That's not
nothing. The fact that you don't need to build a Skadi is also nice. And god, being hit with level 4 frost arrows is just brutal, you go so... slowly.... But if your early game Drow is just farming and stacking Wraith Bands for a nice aura, and not hunting people down and making them slow as fuck so they can't run away, who needs frost arrows?
But how do you fix them? Making them stack with lifesteal would be nice, but it still doesn't make them better than Skadi. I think they need to do that and something else, but I'm not sure what that something else would be. There needs to be some reason to use them.